The Pentagon denied reports of a massacre of 160 Taleban prisoners by opposition forces in southern Afghanistan.

Pentagon spokeswoman Victoria Clarke said extensive U.S. investigations indicate reports of the alleged massacre are simply not credible."There have been reports of a massacre of 160 prisoners by opposition forces. We have worked really hard to run this one to ground and the reports are just not believable," she said.

The reports earlier this week quoted a local Pashtun commander as saying the Taleban prisoners were executed after refusing to surrender in an incident between the southern city of Kandahar and the Pakistani border.

The commander also said several U.S. military personnel were present and tried unsuccessfully to prevent the executions.

Pentagon spokeswoman Clarke acknowledged U.S. soldiers were in the area, but said they reported no such incident."A U.S. liaison team is on the ground with opposition forces in the area. The team has not reported the capture of more than a handful of prisoners. Additionally the team has not reported any information about improper treatment of prisoners and would certainly do so," she said.

The denial was issued prominently at the beginning of the Pentagon's daily briefing on military operations in Afghanistan.

It reflects U.S. concern that international support for those operations could be seriously damaged if anti Taleban forces are linked to revenge killings and other human rights violations.